High speed fiber optic systems may be used in various communication applications, for instance in telecommunication over long transmission distances. A telecommunication network may be classified into various levels such as subscriber networks, regional networks and national networks. The national networks, for example, may exist between different cities where there is a greater demand for higher transmission speeds, for example, above 5 Gbits/sec. In the national networks, for example, dispersion may limit the transmission speeds between transmitters and receivers. Optical dispersion is a fundamental problem for high-speed gigabit networks and is of particular importance as bit rates exceed 2.4 Gbits/sec, for example.
Intersymbol interference (ISI) may also be a problem in digital communications in bandwidth-limited links. The ISI over a communication link may be the dominant power penalty in the link power budget and effectively sets the achievable data rate or transmission distance. The main source of ISI in a fiber-optic system is signal pulse broadening due to fiber dispersion. There may be various types of dispersion in a fiber-optic system, which may comprise modal dispersion, chromatic dispersion and polarization mode dispersion, for example. In a multimode fiber, different mode groups have different velocities, which is called modal dispersion. Chromatic dispersion may be caused by different wavelengths of light having different velocities. The polarization mode dispersion, which may be due to different velocities of different polarizations, may be neglected in multimode fibers.
In order to reduce the dispersion effect, several methods have been proposed and implemented in both electrical and optical domains. The main criteria for a good dispersion reduction method are small power penalty or loss, good integration with current networks, low cost, and adaptability. Dispersion is usually time varying due to environmental change such as temperature variation and is related to fiber length.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.